Death Spell is a rating 10 Wizardry spell and also a Priest Spell. It is considered one of the most powerful and evil spells. The target of this spell is condemned to die of physical exhaustion in a short period of time (few hours) with no chance to be healed by magic potions and most other magical healing spells. However, the caster suffers some permanent damage as well.
The only magic healing widely known to be effective against the Death Spell is Southern Mask Magic style and in fact the most famous Southern Mask Magic user, Pen Ty Kora, is known to have saved worthy adventurers from the Death Spell more than once.